Quick change mold for blow molding apparatus

ABSTRACT

Tooling for a quick change of molds and associated accessories for a blow molding machining for blow molding hollow plastic articles or articles, including a mold (2) that can be opened, with a feed opening (20) for introducing compressed air, an air injection nozzle (4) for the passage of compressed air, a nest (5) to hold the articles (31) after being produced and released by the mold, trim tooling (6) for the removal of the flash (32), characterized by the mold, the nest and the trim tooling being supported by two parallel opposing, spaced apart supporting plates (10), which constitute a modular assembly (1) that is movable lengthwise by a corresponding carriage (50), and by the fact that the air injection nozzle for the introduction of compressed air into the mold is assembled on a movable, self-retaining support (40).

TECHNICAL FIELD

This invention relates to a quick change mold tooling arrangement forblow molding apparatus used for producing hollow plastic articles.

BACKGROUND ART

It is known that in any industrial sector there is the need forproduction lines which are characterized by a high degree of flexibilityso that they can be retooled rapidly in order to adjust production runsto the variable demands and conditions of the market, both as to thequantity and the type of the items being produced.

Such a need is deeply felt in the art of machines for producing hollowplastic items that contemplate the replacement of molds, where moldingparticularly blow molding, takes place, so as to allow the changing ofshape and/or structure of the produced items using only one blow moldingmachine.

Known blow molding machines for producing hollow plastic articlesinclude at least one mold having a mold cavity with the shape of thearticle to be produced, the mold being adapted to be opened and closed.The mold is opened to receive a preform or parison and then closed.After the mold has been closed, compressed air is introduced into theparison contained within the mold through a compressed air feed inletand a corresponding feed nozzle to carry out the blowing of the parisonwhich is expanded and conformed to the inner wall of the mold cavity toacquire the desired shape. The blow molding machine includes at leastone nest or dolly, divided in two sections, that holds the article afterbeing blown and when it has been released by the mold. The machinefurther includes trim tooling for removing the flash from the article.Also, the machine includes several feed lines for supplying coolingwater to the mold and lines for supplying compressed air to the nozzles.

The following operations are required to change the mold and associatedaccessories: disassemble the group of dollies; disassemble the trimtooling; disconnect the cooling lines of the water cooling system forthe molds; disassemble the molds; disconnect the compressed air lines;disassemble the air feed nozzles; reassemble the new tooling; adjust thecenter distance between the mold and the nest or dolly in the newtooling; adjust the position of the trim tooling in the new tooling; andalign the axis of the air feed nozzles with that of the compressed airinlets in the new mold.

It is evident that such a large number of operations requires time andnumerous different tools, that is in contrast with the necessity of arather flexible machine.

Moreover, because it is also necessary to employ specially trainedpersonnel, particularly as far as making adjustments is concerned, theoperative costs of such a working station are very high, especially whencompared with the relatively low price of the finished item.

DISCLOSURE OF THE INVENTION

The object of the invention is to eliminate the above-mentionedinconveniences and to simplify the assembly and the disassemblyassociated with the replacement of the molds and associated tooling in ablow molding machine for producing hollow plastic articles.

This result is achieved by the invention, by providing a modular toolingassembly which includes a mold, a nest or dolly, and trim tooling forthe removal of the flash, wherein the mold, the nest and the trimtooling are assembled to two parallel opposing plates, which are adaptedto be moved apart, which make up the modular assembly that facilitatesmold replacement, and wherein the blowing nozzles are mounted on aremovable self-bearing support.

Essentially, the advantages are represented by the very easy and fastreplacement of molds and associated tooling due to the fact that thenumber of operations and adjustment to be carried out is drasticallyreduced; to the fact that such a replacement can be also performed bynonspecialized personnel, resulting in significant reduction in theoperative costs of the working station; and by the fact that automationof the mold replacement is possible especially in the case of machinefor high capacity production.

These and other advantages and characteristics of the invention can bebetter understood by one skilled in the art through the followingdescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a modular tooling assembly for quickchange of molds, including a mold having a single air feed inlet, withthe mold shown in the closed condition;

FIG. 2 a perspective view of the modular tooling assembly for quickchange of molds of FIG. 1, but with the mold shown in the opencondition;

FIG. 3 is a perspective view of a support with two nozzles for a moldhaving two air feed inlets; and

FIG. 4 is a cross-section view of the nozzle holding support of FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENTS

When reduced to the essential structure and with reference to FIGS. 1and 2 of the drawings, the modular tooling arrangement for quick changeof molds and associated accessories in a blow molding machine forproducing hollow plastic articles, includes a mold 2 adapted to beopened and closed, the mold having a compressed air feed inlet 20 forthe introduction of compressed air through a corresponding blow pin ornozzle 4; a nest or dolly 5 that can be opened to receive a blownarticle and to hold the blown article 31 after it has been released bythe mold 2; and a two-part trim tooling or hollow punches 6 for theremoval of the flash. The two parts of the mold 2 and the nest 5 and thetrim tooling 6 are fixed to two external widely spaced apart, parallelopposing supporting plates 10 so as to provide a modular assembly ormonoblock group 1 which is made movable lengthwise by the correspondingcarriage 50 of the machine. The distance "a" between the vertical axisof the compressed air feed inlet 20 engages of the mold 2 and the medianvertical axis of the nest 5 is preset, that is, adjusted before themodular assembly 1 is assembled on the machine. The nozzle 4 is mountedon a removable, self-bearing support 40 as shown in FIG. 3.

Referring to FIGS. 3 and 4, such a support 40 is made up with a frameincluding a removably mounted plate 41 which is connected at the top toa fixed part or section 100 of the machine, and at the bottom to fourvertical rods 44 for guiding another plate 42 on whose back 410 there isthe head of the stem of a corresponding operating cylinder 110 having avertical axis, the lower side 420 of which is in contact with the baseof the nozzle 4 so as to allow the actuation, that is the insertion intoand the withdrawal from, the compressed air feed inlet 20 of the mold 2.A third plate 43 equipped with a guide boss 45 for the stem of thenozzle 4 is fixed to the lower ends of the above-mentioned vertical rods44. Furthermore, advantageously, the position of the nozzle 4 withrespect to the compressed air feed inlet 20 of the corresponding mold 2is preset. In other words, it is adjusted before the modular assembly 1and the support 40 are assembled on the machine.

The trim tooling 6 are coupled to means of motion in an orthogonaldirection with respect to that the direction of translation x--x of themodular assembly 1.

According to the invention, these means of motion of the trim tooling 6include a cylindrical actuator 60 with its axis orthogonal to the motionof translation x--x of the modular assembly 1.

As an alternative, the trim tooling 6 are assembled on an independentcarriage, not illustrated, which is adapted to be assembled and replacedalong the modular assembly 1.

When the mold 2 needs to be replaced, the water lines 21 for coolingwater and air lines for compressed air are disconnected, and then thewhole modular assembly 1 is removed, without disassembling eachcomponent. A new modular assembly, with an associated mold 2, nest 5 andtrim tooling 6, is mounted in its place. Also, the support 40 for thenozzle 4 is totally replaced with no need for disassembling eachcomponent and no need for a new adjustment of the position of the nozzle4 with respect to the compressed air feed inlet 20.

According to an alternative embodiment and with reference to FIGS. 3 and4, this invention contemplates an embodiment of a mold 2 with twocompressed air inlets 20 for the introduction of compressed air, whichis fed through two corresponding blow pins or nozzles 4 in order toallow, for example, the simultaneous blowing of two articles in twoseparate and distinct mold cavities.

Obviously, the number of compressed air inlets 20 of a mold 2 andassociated blowing nozzles 4 may vary according to the size and shape ofthe item being manufactured.

Referring again to FIGS. 1 and 2, the plates 10 which support the mold2, the nest 5 and the trim tooling 6 are equipped with two connectors 21for the quick connection of the water lines to the cooling water system.

The plates are also equipped with several parallel, transverselyextending plugs or guide rods 11 which represent elements of guidanceand linkage to corresponding drive means 70 that moves the plates 10apart and together.

When in operation, the machine functions as follows. After the preformor parison 31 has been blown and solidified inside the mold 2, theplates 10 are moved apart and the article 31, with associated flash 32still attached, hangs from the opening of the nozzle 4. The carriage 50is activated so as to move the modular assembly 1 as a unit. The nest ispositioned in correspondence with the nozzle 4. At this stage, theplates 10 are moved together, or closed, and the nest 5 holds thearticle 31. At the same time, the nozzle is lifted and is separated fromthe article. After the plates are closed, the cylinder 60 activates thetrim tooling 6 which push or knock the flash 32 from the article.

In summary the details of the operation may vary according to the shape,size, arrangement of the elements, and composition of the material beingused without, however, changing the solution and scope of the claims.

We claim:
 1. Tooling for quick change of molds and accessories in a blowmolding machine for blow molding hollow plastic articles, which includesa mold that can be opened and closed; said mold having a feed opening orinlet for compressed air; a nozzle for compressed air feeding; a nestfor holding the hollow plastic article after being blown and releasedfrom the mold; trim tooling for the removal of flash; and a carriage forproviding relative movement between said nozzle and said mold and nest,comprising said mold, said nest, and said trim tooling being supportedby two spaced apart, parallel and opposing supporting plates forming amodular assembly; said modular assembly having means for securing saidmodular assembly as a unit to said carriage, enabling said modularassembly to be moved as a unit lengthwise by said carriage relative tothe nozzle between a first position at which the nozzle is aligned withthe vertical axis of said feed opening or inlet of said mold and asecond position at which the nozzle is aligned with a median verticalaxis of said nest; and said compressed air feeding nozzle is assembledon a removable self-bearing support, the mouth of said mold, said nest,and said trim tooling on said supporting plates enabling a distance "a"between the vertical axis of said feed opening or inlet of said mold andsaid median vertical axis of said nest and the alignment of said trimtooling relative to said median vertical axis of said nest to beestablished prior to the assembly of the modular assembly on the blowmolding machine, whereby when said modular assembly is mounted on theblow molding machine with said feed opening or inlet of said moldaligned with said nozzle at said first position, said median verticalaxis of said nest and said trim tooling of the modular assembly areautomatically located at said second position.
 2. Tooling according toclaim 1 wherein said support comprises a frame that includes a platewhich on its upper side is removably connected to a fixed part of themachine, and on its lower side mounts four vertical rods for guiding asecond plate on the back of which there is located the head of the stemof a corresponding cylinder which is operable along a vertical axis andthe lower side of which is in contact with the base of the nozzle inorder to allow the actuation of the nozzle, comprising the insertion ofthe nozzle into and the withdrawal of the nozzle from, respectively, thefeed opening or inlet of the mold, and a third plate fixed to the lowerparts of said vertical rods and equipped with a guide boss for thenozzle stem.
 3. Tooling according to claim 1 wherein the position ofsaid nozzle with respect to the feed opening or inlet of thecorresponding mold is variable and is preset prior to the assembly ofthe modular assembly and the support on the blow molding machine. 4.Tooling according to claim 1 wherein said trim tooling includes meansfor moving said trim tooling in a direction that is orthogonal withrespect to the direction of translation (X--X) of the modular assembly.5. Tooling according to claim 4 wherein said means for moving the trimtooling includes a cylindrical actuator with its axis in orthogonalorientation with respect to the direction of translation (x--x) of themodular assembly.
 6. Tooling according to claim 1 wherein said modularassembly includes a mold with two feed openings or inlets through whichcompressedair is fed from two corresponding nozzles (4).
 7. Toolingaccording to claim 1 wherein the number of feed openings or inlets ofsaid mold and the number of nozzles for blowing is dependent upon thesize and shape of the article to be produced.
 8. Tooling according toclaim 1 wherein said supporting plates are equipped with severalconnectors for fast connection of cooling system lines to said moldassembly.
 9. Tooling according to claim 1 wherein said supporting platesare equipped with several parallel and transverse projecting pins whichcomprise elements of guidance and linkage for a drive means of thecarriage that moves said support plates together and apart, respectivelyclosing and opening said mold and enabling said nest to grip andrelease, respectively, the blown article.
 10. Tooling according to claim4 wherein characterized by the fact that the carriage includes a drivemeans that moves said support plates together to close said mold and toenable said nest to grip the blown article, and said means for movingthe trim tooling moves the trim tooling to remove flash from the blownarticle after the support plates have been moved together by the drivemeans.